The present invention relates to releasable fastening systems and, more particularly, to an improvement to hook and loop fastening systems of the type comprising one portion composed of backing material having a hooked surface thereon and another portion composed of backing material having a looped surface thereon. The improvement allows for releasably fastening two components together with the hook and loop materials in shear and is characterized by a planar member having one of the components attached to the end thereof and having outer faces each having one of the portions of the fastening system thereon; and, a U-shaped member having the other of the components attached to the closed end of the U and having inner faces on the sides of the U each having the other of the portions of the fastening system thereon, wherein the U-shaped member is adapted to receive the planar member between the inner faces with the portions of the loop fastening portions in engagement and is further adapted to have at least one side pivoted adjacent the closed end of the U to allow progressive disengagement of the portions of the fastening system.
Hook and loop fastening material as sold by the assignee of the present application under trademark VELCRO is well-known and well-accepted commercially. The basic concept thereof is shown in FIGS. 1 and 2. The fastening system, generally indicated as 10, includes a first portion comprising a first strip of flexible backing material 12 having a loop material 14 on one side thereof. The second portion comprises a second flexible backing material 16 having resilient hooks 18 extending from one side thereof. For purposes of simplicity in the drawings, the hooks 18 are shown enlarged and few in number. In actuality, in the commercial product, the hooks 18 are quite small and are many in number. The hooks can either be T-shaped, as shown, or alternatively, J-shaped, or the like.
Typically, the two portions are attached to two members to be releasably joined as by sewing, ultrasonic welding or adhesive. When the two portions are pushed together in the manner of FIG. 2, the hooks 18 catch in the loop material 14 and resist separation. To separate the portions, they are "peeled" apart as indicated by the arrow 20 in FIG. 3 such that the hooks 18 and the loop material 14 are progressively separated rather than attempting to separate them all simultaneously. In order to separate the portions, the hooks 18 must be deformed in the area of the projections 22 to release the engagement of the hooks 18 with the loop material 14.
Turning now to FIG. 4, the basic problem to be solved by the present invention is depicted. If there were a rigid U-shaped channel 24 as shown having a bar or plate 26 disposed therein; and, if hook and loop fastening systems 10 were disposed between the bar or plate 26 and the sides of the U-shaped channel 24 and attached thereto as with adhesive, the bar or plate 26 would be maintained within the U-shaped channel 24 by the hook and loop fastening systems 10 being what is referred to as "in shear". That is, in order for the bar or plate 26 to be pulled from the U-shaped channel 24, both the stems 28 and the projections 22 of the hooks 18 would have to be deformed in order to break their grip on the loop material 14. Moreover, as opposed to the progressive disengagement normally employed as depicted in FIG. 3, total disengagement would have to be undertaken simultaneously. As a result, hook and loop fastening material operating "in shear" in the manner of FIG. 4 is quite strong. For example, in one test it was found that a representative sample took two pounds of force to separate the portions in the progressive manner of FIG. 3 whereas twenty pounds of force were required to release the materials in the shear direction. Greater insight can be gained with respect to using such hook and loop fastening materials in shear and, in particular, with the problem of separating rigid members joined by hook and loop fastening material by reference to U.S. Pat Nos. 4,271,566 of Perina and 3,475,810 of Mates, both of which are assigned to the assignee of the present application.
From the foregoing, it will be appreciated that hook and loop fastening material operated in shear could be employed to support large loads. Unfortunatly, without a means for releasing the material other than the shear direction or the use of a separate releasing device as described in the above-referenced Mates patent, such use is often impractical.
Wherefore it is the object of the present invention to provide a means for using hook and loop fastening systems in shear while allowing progressive disengagement of the components even when rigid materials are employed.